The invention pertains to devices for storing gases and fluids under pressure. More particularly, the invention relates to pressure vessels that are formed out of flexible materials and that can be made to conform to a variety of shapes.
Typically, pressure vessels capable of containing liquids or gases at significant pressures have involved fixed shape cylinders or spheres formed of high-strength metals such as steel or aluminum. Such pressure vessels, while successful for their designed applications, involve a number of problems. First, such metallic cylinders are relatively heavy compared to the gases or fluids that they contain. Second, pressure cylinders contain all of the gas or liquid in a single space. Should the vessel rupture, the entire vessel is destroyed, often with a violent explosion sending shards of metal in all directions. Third, metallic cylinders have a definite shape and cannot be adapted to fit readily in many space-constrained applications. The present invention involves a number of small cells linked to each other by small conduits. The cells are collected in a flexible matting material that adds to the structural integrity of the cells. A pressure vessel of this type can be lightweight, adaptable to a variety of spaces and unusual applications, and is inherently safer in rupture situations.
Various designs have been developed using linked cell technologies, most in the area of packaging materials. U.S. Pat. No. 4,551,379 issued to Kerr discloses heat-sealable packaging material comprised of interconnected cells formed by laminating two facing sheets of air impermeable material to define designated partitions and passageways. Discontinuities are provided at selected locations in each of the partitions to provide limited communication between the adjacent passages. The packaging material may be cut to the desired length and sealed at one end and then inflated by the insertion of a suitable manifold at the other end and supplying pressurized air. While inflation is maintained, the passages are sealed by a heat-sealing bar trapping the air within the passages.
U.S. Pat. No. 4,096,306 issued to Larson, describes air inflated cushioning material comprising a series of interconnected cells formed by heat-sealing two facing sheets of film together. Here the cells are connected to each other and a central passageway that is used to inflate the cells. After inflation, the entrance to the passageway is then sealed.
U.S. Pat. No. 4,465,188, issued to Soroka et al, is directed to an inflatable packaging structure that includes an envelope with an inner liner. The inner liner located within envelope includes an inflatable first layer and a second or upper inflatable layer formed of flexible sheets of heat sealable plastic material. The sheets are sealed to form zones that are connected to a single valve used for inflation.
U.S. Pat. No. 5,267,646 issued to Inoue et al. describes containers formed of laminated, interconnected cells. The cells are arranged in pairs that can communicate with each other. One chamber is designed to hold powdered, liquid or solid preparations while the second chamber is designed to hold an oxygen absorbent and a desiccant.
U.S. Pat. No. 5,824,392 issued to Gotoh et al., is directed to a method and apparatus for producing an air cushion having a plurality of independent bubbles. The bubbles have communicating portions extending in a continuous direction so that a plurality of them may be filled simultaneously and then individually sealed. A sheet of bubbles is formed by heat-sealing films together having the bubble forming depressions shapes with a hollow tubing communicating portion extending at the center line of the films in a continuous direction. A portion corresponding to the bubble forming depressions communicates with the right and left sides of the communicating portion. Air blown from a nozzle and fed through the communicating portion inflates the bubbles so that the films can be sealed at the communicating conjunction area making each bubble independent.
While other variations exist, the above-described designs involving linked cell technologies are typical of those encountered in the prior art. It is an objective of the present invention to provide a flexible pressure vessel that is capable of maintaining gasses or liquids at relatively high pressures. It is a further objective to provide this capability in a vessel that is light in weight and that presents a significantly reduced risk of injury in rupture situations. It is a still further objective of the invention to provide a pressure vessel that may be easily adapted to a variety of space constraints.
It is yet a further objective to provide a pressure vessel that is durable, easily serviced, and that may be produced inexpensively. It is still a further objective to provide a flexible pressure vessel that is protected against contamination by liquids and gases that it may contain. It is another objective to provide means to increase the pressure handling capabilities of the flexible pressure vessel. It is yet another objective of the invention to provide such increased pressure handling capability with a minimal increase in weight.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.
The present invention addresses many of the deficiencies of prior art flexible container and pressure vessel inventions and satisfies all of the objectives described above.
A flexible pressure vessel providing the desired features may be constructed from the following components. At least one upper dome-shaped cell portion is provided. The upper cell portion is formed from a first sheet of resilient material and has an inner surface, an outer surface, an inner perimeter, an outer perimeter, a border of sheet material surrounding the outer perimeter, and at least one upper passageway portion. The upper passageway portion extends outwardly from the inner perimeter to the surrounding sheet material.
At least one mating lower dome-shaped cell portion is provided. The lower cell portion is formed from a second sheet of resilient material and has an inner surface, an outer surface, an inner perimeter, an outer perimeter, a border of sheet material surrounding the outer perimeter, and at least one lower passageway portion. The lower passageway portion extends outwardly from the inner perimeter to the surrounding sheet material. The upper cell portion is joined to the mating lower cell portion such that a cell is formed. The cell has at least one passageway extending outwardly from the cell for connection to either a passageway of another cell or a valve.
A first ring is provided. The first ring has a first inner circumference, an outer circumference and a first predetermined thickness. The first ring is sized and shaped to fit frictionally over the upper cell portion and surround its outer perimeter. A second ring is provided. The second ring has a second inner circumference, an outer circumference and a second predetermined thickness. The ring second ring is sized and shaped to fit frictionally over the lower cell portion and surround its outer perimeter.
A first flexible blanket is provided. The first blanket has an upper surface, a lower surface and is sized and shaped to cover the upper cell portion and surrounding sheet material. The first blanket is fixedly attached at its lower surface to the outer surface of the upper cell portion and surrounding sheet material. A second flexible blanket is provided. The second blanket has an upper surface, a lower surface and is sized and shaped to cover the lower cell portion and surrounding sheet material. The second blanket is fixedly attached at its lower surface to the outer surface of the lower cell portion and surrounding sheet material. A valve is provided. The valve is connected to the passageway and provides means for controlling a flow of either of gasses and liquids into and out of the cell.
In a variant of the invention, heavy duty stitching is used to attach the first blanket to the second blanket. The stitching penetrates the first and second blankets and the first and second resilient sheets between the upper and lower cell portions and serves to prevent movement of the first and second rings with respect to the upper and lower cell portions.
In another variant, the heavy duty stitching is high-pressure hoop and lock braiding. In still another variant, a cell-shaped sponge is inserted between the upper cell portion and the lower cell portion prior to joining the upper and lower cell portions. The sponge serves to prevent the cell from collapsing after either of gas and liquid is removed from the cell. In yet another variant, the sponge is impregnated with a with a zeolite compound.
In yet a further variant of the invention, either a heat-reflecting plastic film or a metal foil is inserted between at least one of the first blanket and the upper cell portion or the second blanket and the lower cell portion.
In still a further variant, the upper cell portion is joined to the lower cell portion by either radio frequency welding or high strength adhesive. In another variant, either of the first and second blankets is formed of high-strength fiber impregnated material. In still another variant the passageway has a cross-section of between 0.050 and 0.100 inches.
In yet a further variant, the flexible pressure vessel includes an upper retaining plate. The upper retaining plate has a third inner circumference, an outer circumference and a third pre-determined thickness. The upper retaining plate is sized and shaped to fit over the upper cell portion and surround its outer perimeter when the upper cell portion is covered by the first blanket. The third inner circumference is larger than the outer circumference of the first ring.
A lower retaining plate is provided. The lower retaining plate has a fourth inner circumference, an outer circumference and a fourth pre-determined thickness. The lower retaining plate is sized and shaped to fit over the lower cell portion and surround its outer perimeter when the lower cell portion is covered by the second blanket. The fourth inner circumference is larger than the outer circumference of the second ring. Means are provided for attaching the upper retaining plate to the lower retaining plate. When the upper retaining plate is attached to the lower retaining plate, surrounding the upper and lower cell portions and the first and second blankets covering the first and second rings, the pressure capacity of the cell will be increased.
In still a further variant of the invention, the means for attaching the upper retaining plate to the lower retaining plate includes a series of holes. The holes penetrate the upper retaining plate between its outer circumference and the third inner circumference, the lower retaining plate between its outer circumference and the fourth inner circumference and the first blanket, the border of sheet material surrounding the outer perimeter of the upper cell portion, the border of sheet material surrounding the outer perimeter of the lower cell portion and the second blanket. The holes are outside of the outer circumference of the first and second rings.
A series of fastening means are provided. The fastening means are sized and shaped to pass through the series of holes and capable of securing the upper retaining plate to the lower retaining plate. In another variant, the fastening means is a series of bolts and locking nuts. In still another variant, the fastening means is a series of rivets.
In a further variant of the invention, the means for attaching the upper retaining plate to the lower retaining plate includes a series of holes. The holes penetrate the upper retaining plate between its outer circumference and the third inner circumference, the first blanket, the border of sheet material surrounding the outer perimeter of the upper cell portion, the border of sheet material surrounding the outer perimeter of the lower cell portion and the second blanket. The holes are outside of the outer circumference of the first and second rings.
A series of pins is provided. The pins are affixed orthogonally along an upper surface of the lower retaining plate and are sized, shaped and located to fit slidably through the series of holes and extending slightly above an upper surface of the upper retaining plate. A series of welds are used to fixedly attach the pins to the upper retaining plate, thereby securing the upper and lower retaining plates to each other.
In still another variant, a series of cell shaped sponges is provided. A tube is provided. The tube is formed of flexible, gas and liquid impervious material and is sized and shaped to surround the sponges. The sponges are inserted in the tubing at spaced intervals. The encased sponges are inserted between the upper cell portions and the lower cell portions prior to joining the upper and lower cell portions. The tubing extends through the passageways. The sponges serve to prevent the cells from collapsing after either of gas and liquid is removed from the cells. The tube serves to prevent contamination of gas or liquid by the inner surfaces of the upper and lower cell portions.
In yet another, the sponges are impregnated with a zeolite compound.
In a final variant of the invention, the tube is formed from material selected from the group comprising: thermoplastic polyurethane elastomer, polyurethane polyvinyl chloride, polyvinyl chloride, and thermoplastic elastomer.
An apparatus for fabricating a flexible pressure vessel includes first and second rolls of planar resilient material. First and second thermal die stamping stations are provided. The stamping stations are capable of forming the upper and lower cell portions. Means are provided for moving resilient material from the first and second rolls of planar resilient material into the first and second thermal die stamping stations.
A radio frequency welder is provided, the welder is capable of joining the upper cell portion to the lower cell portion. Means are provided for moving the first and second cell portions into the radio frequency welder. A series of first and second rings is provided. The first ring is sized and shaped to fit frictionally over the upper cell portion and to surround its outer perimeter. The second ring is sized and shaped to fit frictionally over the lower cell portion and to surround its outer perimeter.
First and second rolls of high-strength fiber impregnated blanket material are provided. Means are provided for attaching the first and second blankets over the upper and lower cell portions. Means are provided for attaching a valve to a passageway of a cell.
In variant of the apparatus for fabricating a flexible pressure vessel, a series of cell-shaped sponges are provided. Means are provided for inserting the cell-shaped sponges between the upper and lower cell portions. In still another variant, first and second rolls of either heat-reflecting plastic film or metal foil are provided. Means are provided for attaching either heat-reflecting plastic film or metal foil to the outer surface of at least one of the upper cell portion and the lower cell portion.
In another variant, means are provided for moving the blanketed cells to a high pressure hoop and lock braiding machine for stitching. In yet another variant, a series of cell shaped sponges is provided. A tube is provided. The tube is formed of flexible, gas and liquid impervious material and is sized and shaped to surround the sponges. Means are provided for inserting the sponges in the tube at spaced intervals. Means are provided for inserting the encased sponges between the upper cell portions and the lower cell portions prior to joining the upper and lower cell portions. The tube extends through the passageways.
In a final variant of the apparatus for fabricating a flexible pressure vessel means are provided for positioning an upper retaining plate to fit over the upper cell portion and surround its outer perimeter when the upper cell portion is covered by the first blanket. Means are provided for positioning a lower retaining plate to fit over the lower cell portion and surround its outer perimeter when the lower cell portion is covered by the second blanket.
Means are provided for producing a series of holes that penetrate the upper retaining plate between its outer circumference and the third inner circumference, the lower retaining plate between its outer circumference and the fourth inner circumference and the first blanket, the border of sheet material surrounding the outer perimeter of the upper cell portion, the border of sheet material surrounding the outer perimeter of the lower cell portion and the second blanket. The holes are outside of the outer circumference of the first and second rings. Means are provided for inserting and securing fastening means through the holes, thereby securing the upper and lower retaining plates to each other.
A method for fabricating a flexible pressure vessel includes the following steps: Providing first and second rolls of planar resilient material. Providing first and second thermal die stamping stations. Moving the first and second rolls of planar resilient material into the first and second thermal die stamping stations. Forming upper and lower cell portions in the first and second thermal die stamping stations.
Providing a radio frequency welder. Moving the first and second cell portions into the radio frequency welder. Joining the upper cell portion to the lower cell portion in the radio frequency welder. Fitting a first ring frictionally around the outer perimeter of the upper cell portion and fitting a second ring frictionally around the outer perimeter of the lower cell portion. Providing first and second rolls of either of heat-reflecting plastic film and metal foil. Attaching either heat-reflecting plastic film or metal foil to the outer surface of at least one of the upper cell portion and the lower cell portion.
Providing first and second rolls of high-strength fiber impregnated blanket material. Attaching the first and second blankets over the upper and lower cell portions and either the heat-reflecting plastic film or metal foil. Stitching through the first and second blankets and the resilient material surrounding the upper and lower cell portions. Providing a valve and attaching the valve to a passageway of a cell.
A variant of the method for fabricating a flexible pressure vessel includes the following additional steps: Providing a series of cell-shaped sponges impregnated with a zeolite compound. Inserting the cell-shaped sponges between the upper and lower cell portions prior to joining the upper and lower cell portions.
Another variant includes these steps: Providing first and second rolls of either heat-reflecting plastic film or metal foil. Attaching either heat-reflecting plastic film or metal foil to the outer surface of at least one of the upper cell portion and the lower cell portion.
Still another variant includes moving the blanketed cells to a high pressure hoop and lock braiding machine prior to stitching. Yet a further variant of the method includes the following steps: Providing a series of cell shaped sponges. Providing a tube. The tube is formed of flexible, gas and liquid impervious material and is sized and shaped to surround the sponges. Providing means for inserting the sponges in the tube at spaced intervals. Providing means for inserting the encased sponges between the upper cell portions and the lower cell portions prior to joining the upper and lower cell portions. Extending the tube through the passageways.
In yet another variant of the invention, the method for fabricating a flexible pressure vessel includes the following additional steps: Providing upper and lower retaining plates. Providing a series of holes. The holes penetrating the upper retaining plate between its outer circumference and the third inner circumference, the lower retaining plate between its outer circumference and the fourth inner circumference and the first blanket, the border of sheet material surrounding the outer perimeter of the upper cell portion, the border of sheet material surrounding the outer perimeter of the lower cell portion and the second blanket. The holes are outside of the outer circumference of the first and second rings. Inserting and securing a series of fastening means through the holes, thereby securing the upper and lower retaining plates to each other.
In still a further variant, a series of cell shaped sponges is provided, as is a tube. The tube is formed of flexible, gas and liquid impervious material and is sized and shaped to surround the sponges. The sponges are inserted in the tube at spaced intervals, the encased sponges are wound with high-strength filament material. The filament wound tubing containing the sponges is inserted between the upper cell portions and the lower cell portions prior to joining the upper and lower cell portions with the tube extending through the passageways. The sponges serve to prevent the cells from collapsing after either gas or liquid is removed from the cells. The tube serves to prevent contamination of either gas or liquid by the inner surfaces of the upper and lower cell portions and the filament material serves to increase strength of the tubing.
In yet a further variant, the sponge is impregnated with a zeolite compound.
In still a further variant of the invention, the tube is formed from material selected from the group comprising thermoplastic polyurethane elastomer, polyurethane polyvinyl chloride, polyvinyl chloride and thermoplastic elastomer.
In another variant, the high-strength filament material is selected from the group comprising KEVLAR(copyright), carbon fiber, steel, stainless steel and nylon.
In still another variant, an apparatus for fabricating a flexible pressure vessel further comprises a series of cell shaped sponges and a tube. The tube is formed of flexible, gas and liquid impervious material and is sized and shaped to surround the sponges. Means are provided for inserting the sponges in the tube at spaced intervals. Means are provided for winding the encased sponges with a high-strength filament material. Means are provided for inserting the filament wound tubing containing the sponges between the upper cell portions and the lower cell portions prior to joining the upper and lower cell portions with the tube extending through the passageways.
In yet another variant, an apparatus for fabricating a flexible pressure vessel further comprises means for positioning an upper retaining plate to fit over the upper cell portion and surround its outer perimeter when the upper cell portion is covered by the first blanket. Means are provided for positioning a lower retaining plate to fit over the lower cell portion and surround its outer perimeter when the lower cell portion is covered by the second blanket. Means are provided for producing a series of holes. The holes penetrate the upper retaining plate between its outer circumference and the third inner circumference, the lower retaining plate between its outer circumference and the fourth inner circumference and the first blanket, the border of sheet material surrounding the outer perimeter of the upper cell portion, the border of sheet material surrounding the outer perimeter of the lower cell portion and the second blanket. The holes are outside of the outer circumference of the first and second rings. Means are provided for inserting and securing fastening means through the holes, thereby securing the upper and lower retaining plates to each other.
In still another variant of the invention, a method for fabricating a flexible pressure vessel further comprises the following steps: Providing a series of cell shaped sponges. Providing a tube formed of flexible, gas and liquid impervious material that is sized and shaped to surround the sponges. Inserting the sponges in the tubing at spaced intervals. Winding the encased sponges with a high-strength filament material. Inserting the filament wound tubing containing the sponges between the upper cell portions and the lower cell portions prior to joining the upper and lower cell portions with the tubing extending through the passageways.
In a final variant of the invention a method for fabricating a flexible pressure vessel further comprises the following steps: Providing upper and lower retaining plates. Providing a series of holes. The holes penetrate the upper retaining plate between its outer circumference and the third inner circumference, the lower retaining plate between its outer circumference and the fourth inner circumference and the first blanket, the border of sheet material surrounding the outer perimeter of the upper cell portion, the border of sheet material surrounding the outer perimeter of the lower cell portion and the second blanket. The holes are outside of the outer circumference of the first and second rings. Inserting and securing a series of fastening means through the holes, thereby securing the upper and lower retaining plates to each other.
An appreciation of the other aims and objectives of the present invention and an understanding of it may be achieved by referring to the accompanying drawings and the detailed description of a preferred embodiment.